Northern California's strongest earthquake in at least 13 years rocked a 350-mile wedge of the state in two sweeps of at least 10 seconds each yesterday, toppling light poles, knocking out power and shaking skyscrapers. There were no reports of serious injuries, and damage apparently was minor.

The tremor, which registered 5.9 on the Richter scale, hit at 10:06 a.m. PDT. It was the third quake in less than four months to be felt throughout the San Francisco Bay area.

The University of California Seismographic Station in Berkeley placed its epicenter 18 miles north of Hollister on the Calaveras Fault, but the quake was felt well into southern California, with vibrations recorded as far south as Encino, 15 miles north of Los Angeles.

"It seemed to be the rolling-type quake where everything moves back and forth but doesn't cause a lot of damage," said a sheriff's deputy at Hollister, about 80 miles south of San Francisco.

Some cracked walls and ceilings were reported in San Francisco, and a small crowd gathered to gape at a four-foot crack in the side of the Toronto Dominion Bank, a brick office building in the heart of the financial district.

Across town at the city zoo, a worker reported that at the first vibrations, "the birds were vocalizing, the elephants looked nervous, walked in cricles and began tapping their trunks on the ground - and we can't get the gorillas to go back into their house." CAPTION: Picture, Grocery owner in Salinas, Calif., surveys damage caused by earthquake., AP